Musings on astronomy and science

Menu

More on JWST

Anyway, the bill passed, and thanks to Senator Milukski (D-MD) the James Webb Space Telescope is getting funding. Of course, then I learn from Badastronomy.com that Congress, in its infinite wisdom, didn’t quite give NASA enough money to fully cover the cost. And so, NASA is going to have to redirect more money to JWST from somewhere else, and it sounds like they’ll be taking it from solar system exploration. That just seems wrong. I mean, I’m a stellar astronomer; I would still choose to save JWST if I had to do it again… but I like the planets, and it’s a bit hard to conscience giving THAT up.

Fact is, I don’t particularly like JWST to begin with. It’s being pitched as a successor to Hubble, but it’s not (not any more, anyway). It’s an infrared telescope (1-28 microns; visible light is 0.3-0.7 microns), but it’s no longer the only one. It may be a successor to Spitzer (3-180 microns), but we’ve already got Herschel (which is farther into the infrared, 55 microns to 670 microns, WISE (3.4-22 microns, which was a survey, granted), WFIRST (couldn’t find any information)… We’re overloading on one kind of observing. There are no UV missions or space interferometers being planned (there is one X-ray satellite, but it’s so far down the list (ie, #4 on the Decadal Review list) that it won’t possibly be funded by 2020. Instead we get another, bigger and badder IR telescope.

Add to that, JWST will not have the kind of life Hubble’s had. Because of its far infrared bands, it’ll be stuck at L2, a point in space millions of kilometers away; we won’t be able to service it should something break, or replace the cryogen (and to be honest, we’re not likely to have the technology to do this well for YEARS, but whatever). Once that runs out (in about five years), JWST’s farthest-infrared instrument, MIRI, won’t work. We’ll probably get to keep some of the Near-Infrared bands visible with the other instruments, though.

Now, to be clear, I understand WHY the limits are what they are. To see into the far-infrared at the required resolution you NEED an enormous and expensive mirror; to keep it cold enough to see those infrared bands you NEED a cryogen tank; and you NEED to be far enough away from the Earth that it won’t contaminate your results… the science WILL be fantastic, and we’re certain to discover groundbreaking new things. The problem is that JWST has sucked up basically the entire astrophysics budget. Many missions have been cancelled to make way for it, and now it’s spilling out until it takes over all of NASA. We’re putting all our money into one mission, and if it blows up or fails to unfold properly, that’s ALL the astrophysics budget for the forseeable future. I’m not ok with THAT.

But then again, it’s all astrophysics has, and if it’s cancelled, NASA certainly isn’t gonna get any money to do anything else… so JWST has my reluctant support.